"The Sisterhood of the Traveling Pants" is supposed to be a teenage chick flick, but I have to confess that at the emotional high point, a tear formed in the eye of this middle-aged man (who, of course, wiped it away before anyone else could notice).

The poignancy seems as unlikely as the story line: Four young women decide to take turns wearing the same thrift store jeans over the summer. That their vastly different dimensions would be able to fit into the same pair stretches the laws of fashion as well as credulity. It also seems unlikely that such different girls would be fast friends -- we're told they've been together since their mothers met in a prenatal aerobics class.

Ah, but it's magic.

Viewers who put aside their skepticism will be rewarded as the girls embark on their first summer apart: Carmen (America Ferrera), a full-figured and volatile Puerto Rican, plans to spend some quality time with her father, who has moved to another state after divorce. Confident, blond and athletic Bridget (Blake Lively) is heading for a soccer camp in Mexico. Soft-spoken, artistic Lena (Alexis Bledel of "Gilmore Girls") is visiting her grandparents in Greece. Sarcastic and rebellious Tibby (Amber Tamblyn of "Joan of Arcadia") is remaining in Bethesda, stocking shelves at a discount store and working on a cynical documentary.

Though the characters seem easily identifiable types, they prove to be more fully realized. That will come as no surprise to the legions of teenage girls who have devoured Ann Brashares's best-selling debut novel and its two sequels. Like Judy Blume, Brashares has captured the voices of young women who are as likely to share their innermost secrets and dreams as they are to share a pair of bluejeans.

Of course, there are rules. But suffice to say that each girl agrees to wear the pants for a week before passing them on to the next, and, in turn, document the luck the pants bring.

But like all best-laid plans -- and well-loved jeans -- some things start to fall apart. Carmen's fairy tale reunion with her dad (Bradley Whitford, as socially clueless as his "West Wing" character) is derailed; it turns out he has a new family. Bridget is determined to perfect her ability to score on and off the soccer field, though thankfully for squeamish dads, much of the latter is left off camera. Lena is torn between devotion to family and her interest in a young Greek hunk. And Tibby's negativity is worn away by a precocious pest (Jenna Boyd) who sees beneath her crusty facade.

The emotional story and fine acting are enough to make this a must-see movie for teen girls. The real surprise is that they can make a grown man cry.

The Sisterhood of the Traveling Pants (119 minutes, at area theaters) is rated PG for some sensuality and language.

From left, America Ferrera, Amber Tamblyn, Alexis Bledel and Blake Lively play best friends who share stories and jeans during a summer apart.